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Choosing the proper ADC Driver Differential Amplifier

Question asked by YYHH on Oct 7, 2011
Latest reply on Oct 7, 2011 by charlyelkhoury

Hi,

 

I took a look at the ADC Driver Selection Table and I have doubts about what would be the best fit for my application.

 

I will use a 105 MSPS - 14bit ADC sampling a 35MHz IF signal at 88MHz.

 

When I try to compare the Diff Amplifiers, I can see, for example, amplifiers like ADL5562 with high 3dB BW and very good 2nd and 3rd Harmonic distortions (104dBc and 87dBc), But what's the point in choosing amplifiers with so high BW if I need less than 800MHz GBW??

So I checked on the ADA4950 parameters which has a 750MHz 3dB-BW, but its distortion parameters are not so good (80dBc and 84dBc). I'm a bit confused about that.

 

How should I choose my differential driver? How to properly compare differential amplifiers?

And finally, should I better use this king of configuration:

ADA4950-1_fbs.png

Or this one:

 

ADL5561.png

What are the pros/cons?

 

Thanks,

 

YH.

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